the first type is in Copper-nickel and issued 1395 (1975), 1400 (1980), 1406 (1986) and 1410 (1990), only with islamic dates;
the second type is just a subtype, also Copper-nickel, 1418 / 1998 (only 50 B.) and 1420 / 1999 with islamic and gregorian dates;
the third type is a new material, Nickel plated steel, only minted in 1428/2008, but the design is still as the first types;
the fourth type has a redesigned coat of arms, so I think it should be have a new entry in the catalogue. This type is minted since 1431/2010. Here are photos of the last two types to compare (left one 2008, right 2010):
25 Baisa:
50 Baisa:
I think this should be two different coin types.